Question

1] What is ZX applied to |0>?
2] What is ZX applied to H|0>?
3] Suppose we have a qubit in the state |ψ⟩. We know that if we measure it in the standard basis, the probability of getting a 0 is 29. Now, if we instead first apply a Hadamard gate and then measure the resulting qubit H|ψ⟩ in the sign basis, what is the probability of getting a +?